1. Field of the Invention
The present invention relates to a wire dot printer head provided in a wire dot printer and more particularly to a wire dot printer head having an armature stopper against which an armature comes into abutment when it has pivoted from a printing position to a stand-by position.
2. Description of the Background Art
Heretofore there has been known a wire dot printer head wherein an armature with printing wire connected thereto is moved pivotally between a printing position and a stand-by position and a tip of the wire is caused to strike against printing paper when the armature is pivoted to the printing position, to effect printing.
Such a wire dot printer has an armature stopper against which an armature comes into abutment when it has pivoted from the printing position to the stand-by position. By provision of the armature stopper, it is possible to absorb a shock induced when the armature has pivoted to the stand-by position, thereby suppress the rebound of the armature and prevent the occurrence of such inconveniences as double striking caused by rebound and ribbon hooking. As an example of the armature stopper there is known a structure in which an elastic sheet made of rubber and a stainless steel plate are superimposed one on the other. The armature stopper is disposed in a direction in which the armature when pivoted to the stand-by position comes into abutment against the stainless steel plate. Such a stainless steel plate is formed so that its surface for abutment against the armature is flat.
However, with the recent tendency to a higher printing speed and a higher printing pressure, the impact force induced when the armature having pivoted to the stand-by position comes into abutment against the armature stopper is becoming more and more strong.
With such an increase of the impact force, the portion of the stainless steel plate as part of the armature stopper which portion comes into abutment against the armature is chipped or deformed, with consequent change in the printing stroke of the armature, occurrence of variations in print timing and printing pressure for each wire, and deterioration of the print quality.
Further, the plate may be damaged with the impact force induced upon abutment of the armature against the armature stopper, and if broken plate pieces scatter, the wire dot printer head may be heavily damaged.
Accordingly, it is an object of the present invention to suppress chipping or deformation of a hard plate of an armature stopper for abutment against an armature when the armature having pivoted from a printing position to a stand-by position comes into abutment against the armature stopper, and thereby improve the durability of the armature stopper.
It is another object of the present invention to prevent an armature from striking against burrs even when a hard plate which constitutes an armature stopper is burred in the course of fabrication of the armature stopper, and prevent cracking or the like of the armature and the hard plate caused by striking of the armature against the burrs.
It is a further object of the present invention to prevent scattering of broken hard plate pieces even when a hard plate which constitutes an armature stopper is broken upon abutment thereof against an armature.
The above objects of the present invention are achieved by a novel wire dot printer head according to the present invention.
In the novel wire dot printer head of the present invention, an armature stopper against which an armature having pivoted from a printing position to a stand-by position comes into abutment is formed by punching an integrally bonded laminate of an elastic plate and a hard plate, the punching being carried out from the hard plate side to warp the armature so that the hard plate side is convex in shape.